Left ventricular function at rest and arrhythmia analysis prior to hospital discharge allows prediction of a portion of the 10-15 percent of patients who will die suddenly within six months of discharge after acute myocardial infarction. Using new non-invasive radionuclide cineangiographic techniques which permit study during exercise and hence provide more complete assessment of cardiac function than previously available, we propose to determine the feasibility of improving prognostic capability after acute MI. Better prediction might allow appropriate application of medical and surgical therapy prophylactically in high risk patients.